In an image forming device such as a laser printer, a frame is movably or detachably provided to a main body casing, and a toner box accommodating toner therein is mounted in the frame.
The toner box includes concentric dual cylinders including an inner hollow cylinder in which toner is accommodated and an outer hollow cylinder rotatably supporting therein the inner hollow cylinder.
A peripheral wall of the inner cylinder is formed with an opening (internal opening). A toner seal is provided on an outer peripheral surface of the inner cylinder to surround a perimeter of the opening. A peripheral wall of the outer cylinder is also formed with an opening (external opening) corresponding to the internal opening.
Upon alignment of the internal opening with the external opening as a result of rotation of the inner cylinder relative to the outer cylinder, toner can be supplied from the inner cylinder to the outside of the toner box. Further, when the peripheral wall of the outer cylinder covers the internal opening as a result of rotation of the inner cylinder relative to the outer cylinder, communication of the inside of the inner cylinder with the outside of the toner box is shut off, to avoid leakage of the toner from the inner cylinder. With this closure state, the toner box is attached to or detached from the frame.
The toner seal is made from a foaming material having elasticity, and is pressedly interposed between the inner peripheral surface of the outer cylinder and the outer peripheral surface of the inner cylinder at the perimeter of the internal opening. Thus, the toner seal prevents toner from leaking into a space between the inner peripheral surface and the outer peripheral surface.